Mesh effect stiffness

[20021244]

Hi all, 

According to what I know, mesh density does not affect natural frequencies. I have performed a modal analysis for a model with different element sizes. For the lower modes, the natural frequencies do not differ significantly, but when extracting the higher modes, the differences between the natural frequencies vary greatly. I have two questions:

1. How does mesh density affect the stiffness of the model?  

2. Why does mesh density affect the higher modes?

[Deepak]

 

Hi,

The frequency is influenced by stiffness, which in turn is determined by the size of the element. This is particularly important when the model is thin and subject to bending. Increasing the number of elements through the thickness improves the accuracy of the bending stiffness calculation. Higher modes involve complex mode shapes (subject to bending), which makes mass density dependency more at higher modes.

The following article may be helpful in this context:

Why does the mesh size affect my modal analysis results?

Modal analysis. Results differ significantly depending on mesh size

Thanks,
Deepak

 

[20021244]

I have read the above explanation, but it is not helpful to me. Please explain it to me in a simpler way.